N°352-353Content

In recent years, increased concern about global warming and climate change has made it desirable for roadwork engineers to tackle environmental issues. In addition, the increase in temperatures during summer has also become a serious problem in Japan. In particular, as the surface of asphalt pavements may reach 60°C in summer, it is thought to be a factor of another emerging issue known as the "urban heat island phenomenon" which significantly affects the thermal comfort of pedestrians. In general, high surface temperatures influence the performance of pavement surfaces, such as in terms of rutting, aging and fatigue. Bearing in mind these problems, it can be said that a reduction in surface temperature has become an increasingly important issue, in terms of sustainability as well as the environment.

Past studies have indicated that making surfaces lighter to reflect both visible and infrared rays (i.e. sunlight) is the most practical way of mitigating road heat. However, from the perspective of driver visibility, dark surfaces such as black or grey are preferable, since drivers are used to such surfaces. In addition, taking into account onsite workability during construction, surface treatment based on paint coatings is a practical way to handle the issue on existing surfaces. For these reasons, a new surface treatment technology called "solar heat-blocking pavement" has been developed and applied in anticipation of reducing surface temperatures and mitigating urban heat.

This paper highlights the basic concept behind the technology and addresses the environmental and practical effects through experiments and computer simulations.